题目
Given a positive integer c, how many integers are greater than c and less than 2c?
解析
给定一个正整数\(c\),有多少个整数大于\(c\)且小于\(2c\)?
- 假设\(c = 3\),那么\(2c=6\),大于\(3\)且小于\(6\)的整数有\(4\)和\(5\),共\(2\)个,而\(3 - 1=2\)。
- 假设\(c = 4\),那么\(2c = 8\),大于\(4\)且小于\(8\)的整数有\(5\)、\(6\)、\(7\),共\(3\)个,而\(4-1 = 3\)。
一般地,大于\(c\)且小于\(2c\)的整数为\(c + 1,c + 2,\cdots,2c-1\),一共有\((2c - 1)-(c + 1)+1=2c-1-c-1 + 1=c-1\)个。
所以答案是\(C\)。